flexible polyimide aerogel cross-linked by poly(maleic
TRANSCRIPT
Flexible polyimide aerogel cross-linked by poly(maleic anhydride-alt-alkylene)
Haiquan Guo Ohio Aerospace Institute
Mary Ann B. Meador NASA Glenn Research Center
Brittany Wilkewitz NASA Glenn Research Center LERCIP internship 2013
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National Aeronautics and Space Administration
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Mar-17-2014
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http://royal-tarts.deviantart.com/art/Olaf-GIF-4-Melting-Request-426015061
http://delicious-to-c.blogspot.com/2013/12/frozen-2013.html
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Why aerogels?
• Made by removing solvent from wet gels without collapsing the structure
• High porous solids • Low density • High surface area • Good thermal insulation material
• reduces heat transfer (convection, conduction, and radiation)
Sol Aerogel Gel
http://en.wikipedia.org/wiki/Aerogel
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Potential applications of aerogels
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http://spinoff.nasa.gov/spinoff2001/ch5.html
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Inflatable aerodynamic decelerators
Astronaut EVA suits
Habitat structures Cyrotanks
Potential applications of aerogels National Aeronautics and Space Administration
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What should be considered for real application?
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• Flexible • Strong • Less dusty • Hydrophobic • Low cost
ybic
Silica aerogel is fragile • Light weight • High porous • High surface area • Low thermal
conductivity
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Hydropho• Low cost
bicermal tivity
Better mechanical properties and environmental stability are needed…
Cross-linked polyimide aerogels Cross-linkers
M. A. B. Meador and H. Guo, LEW-18864-1, US patent application No. 61/594,657
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octa(aminophenyl)silsesquioxane (OAPS)
1,3,5-triaminophenoxybenzene (TAB)
O O
H2N NH2O
H2N
OOO
O
O
O +
O O
COOH
HR
H O O
HOOC
O
O
O
O
N N
25 H2N R NH226
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polyimide oligomer
OAPS
catalyst
OAPS
• Two cross-linkers with amine functional groups
• Various polyimide oligomer backbones using different dianhydrides and diamines
• Chemical imidization
H. Guo, et al. ACS Appl. Mater. Inter., 2012, 4, 5422. M. A. B. Meador, et al. ACS Appl. Mater. Inter., 2012, 4, 536. H. Guo, et al. ACS Appl. Mater. Inter., 2011, 3, 546.
• Low density and shrinkage • High porosity, surface area, and
modulus • Moisture resistant • Low dielectric constant and
thermal conductivity • Can be metalized with gold • Flexible thin film
Cross-linked polyimide aerogels National Aeronautics and Space Administration
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M.A. B. Meador, et al. ACS Appl. Mater. Inter., 2012, 6346.
Problems of previous cross-linked polyimide aerogels
• OAPS cross-linker is expensive • TAB cross-linker is not commercially available, requires custom
synthesis • Contact angle for the moisture resistant polyimide aerogel is 85-90o
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• Explore commercially available and less expensive cross-linkers
• Look for less expensive monomers that might impart flexibility, hydrophobicity, etc.
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Objectives
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Commercially available poly(maleic anhydride)s as cross-linkers
poly (maleic anhydride-alt-1-octadecene) (PAMO) Mn 30,000-50,000
poly (isobutylene-alt-maleic anhydride) (PIMA) Mw ~6000
poly(ethylene-alt-maleic anhydride) (PEMA) Mw 100,000-500,000
Network formation using poly(maleic anhydride)s as cross-linkers
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polyimide oligomer 13
R: H, CH3, CH2(CH2)xCH3 R’: H, CH3
Cross-linker
imidization
BPDA
Polyimide oligomer
• n=20,10 w/w% • Polyimide oligomers • ODA+BPDA • three cross-linkers ODA
PMAO
PIMA
O NH2H2N +
OH2N NH
O
CO
HOOC
CHN
COOH
O NH2
(n+1) n O O
O
O O
O
n
PEMA
H. Guo and M. A. B. Meador LEW-19108-1
NMR and FTIR spectra prove imidization was completed
13C nuclear magnetic resonance (NMR)
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Typical Fourier transform infrared (FTIR) spectrum of aerogels
Absent • 1860 cm-1 unreacted anhydride • ~1807 & 980 cm-1 isoimide • ~1660 cm-1 ⱱ amic acid C=O • ~1535 cm-1 ⱱ amide C-N
1774 cm-1 asymmetric ⱱ imide C=O
1377 cm-1 ⱱ imide C-N
1716 cm-1
symmetric ⱱ imide C=O
CH2 stretching vibrations
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imide carbonyl
aromatic ether carbon of ODA
aliphatic carbons
aromatic carbon
PMAO
PIMA
PEMA
Density, shrinkage, and porosity National Aeronautics and Space Administration
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PEMA PIMA PMAO
Den
sity
(g/c
m3 )
0.00
0.05
0.10
0.15
0.20
PEMA PIMA PMAO
Shrin
kage
(%)
0
5
10
15
20
25
PEMA PIMA PMAO
Poro
sity
%
0
20
40
60
80
100
• PMAO cross-linked aerogel has the lowest shrinkage
• PEMA cross-linked aerogel has the highest density, the highest shrinkage, and the lowest porosity
PEMA PIMA PMAO
Sur
face
Are
a (m
2 /g)
0
100
200
300
400
500
Pore Size (nm)
7 10 20 30 40 50 60 70 80P
ore
Vol
ume
(cm
3 /g)
0.0
0.5
1.0
1.5
2.0PMAO PIMA PEMA
N2 adsorption/desorption shows the aerogels have mesoporous structure
• PMAO cross-linked aerogels have no pores larger than 40nm
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23nm
Scanning electron microscope (SEM) images
• PMAO and PEMA cross-linked aerogels have µm size cavities • The polymer fibers in the cavities are much longer than the polymer
fibers outside of the cavities • PIMA cross-linked aerogels have more densely packed structure
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Small weight loss before decomposition of polyimide backbone is due to cross-linker
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www nasa gov1
PMAO
PIMA
PEMA
PEMA PIMA PMAO
Mod
ulus
(MPa
)
10
100
Compression tests were performed on the aerogels by compressing to 80%
• Higher or similar modulus compared to TAB or OAPS cross-linked polyimide aerogels made with BPDA and ODA
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Strain
0.0 0.2 0.4 0.6 0.8
Stre
ss (M
Pa)
0
2
4
6
8
10
PMAOPIMAPEMA
Density (g/cm3)
0.05 0.10 0.15 0.20 0.25
Mod
ulus
(MPa
)
1
10
100
TAB-ODA OAPS-ODAPMAO-ODA
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PMAO was down selected as the cross-linker for the following study
• Lower density
• Higher porosity
• Lowest shrinkage
• Highest modulus
PMAO
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• Same or even higher flexibility
• Further reduce cost
• Increase hydrophobicity
Replacing ODA by PPG-230 or PPG-400 in polyimide oligomers
poly(propylene glycol) bis(2-aminopropyl ether) Mn 230 or 400
(PPG-230 or PPG-400)
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Polyimide oligomers made with combination of of PPG/ODA and BPDA
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NH2 +
NH
O
CO
HOOC
CHN
COOH
(n+1) n O O
O
O O
O
H2N X
H2N X
n
X NH2
polyimide oligomer R: CH2(CH2)xCH3 R’: H
imidization
BPDA
Polyimide oligomer
O NH2H2N
PPG-230 or PPG-400,0-60%
ODA
H. Guo and M. A. B. Meador LEW-19108-1
• n : 10-30 • 10 w/w% • PMAO as cross-linker • Polyimide oligomers: PPG/ODA +BPDA
R: H, CH3, CH2(CH2)xCH3 R’: H, CH3
Cross-linker
imidization
BPDA
Polyimide oligomer
• n=20,10 w/w%• Polyimide oligomers • ODA+BPDA • three cross-linkers ODA
PMAO
PIMA
O NH2H2N +
OH2N NH
O
CO
HOOC
CHN
COOH
O NH2
(n+1) n O O
O
O O
O
n
PEMA Polyimide oligomers
0
10
20
30
40
50
60
10
1520
2530
01020304050
Shrin
kage
(%)
nPPG %
0.000.050.10
0.15
0.20
0.25
0.30
0.35
10
1520
2530
01020304050
Den
sity
(g/c
m3 )
n
PPG%
Density, Shrinkage, and Porosity
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PPG-230 PPG-400
70
75
80
85
90
95
100
10
1520
2530
01020304050
Poro
sity
(%)
n
PPG%
• Type and percentage of PPG affect the density, shrinkage and porosity
• At 60% PPG-400, the aerogels shrink the most, resulting in high density and low porosity
• The higher the PPG-230 %, the larger the pore sizes • The higher the PPG-400 %, the lower the pore volume
Increment of % and molecular weight of PPG decrease the surface area
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0
100
200
300
400
500
10
1520
2530
01020304050
Surfa
ce a
rea
(m2 /
g)
n
PPG%
PPG-230 PPG-400
Pore size (nm)7 10 20 30 40 50 60 70 80
Por
e V
olum
e (c
m3 /
g)0.0
0.5
1.0
1.5
2.0 no PPG30 % PPG-230 60 % PPG-230 30%-PPG-40060%- PPG-400
Increasing % or molecular weight of PPG causes densely packed fiber structures
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0% PPG 30 % PPG-230
60% PPG-230 30% PPG-400
TGA curves show Td and char yield decrease with increasing aliphatic groups
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Compression tests show aerogels with n=20 have a higher modulus
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1
10
100
10
1520
2530
01020304050
Mod
ulus
(MPa
)
n
PPG-230 %
• The higher the density, the higher the modulus • The aerogels with PPG-230 have lower modulus than the
aerogels without PPG-230
Density (g/cm3)
0.00 0.05 0.10 0.15 0.20 0.25
Mod
ulus
(MPa
)
1
10
100
TAB-ODA OAPS-ODAPMAO-ODAPMAO-PPG/ODA
60% PPG-230, 124o 30% PPG-400, 121o 30% PPG-230, 99o
Contact angle testing shows more hydrophobic aerogels were produced
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0 10 20 30 40 50 60 70
Con
tact
ang
le (o
)
0
25
50
75
100
125
150
PPG-230 PPG -400
Summary • New aerogels made with amine capped polyimide oligomers and cross-
linked by poly(maleic anhydride)s were synthesized
• The poly(maleic anhydride) cross-linked ODA capped aerogels have higher or similar modulus values compared to TAB or OAPS cross-linked ODA aerogels
• PMAO cross-linked aerogels have lower density and higher porosity, the lowest shrinkage and the highest modulus
• Addition of PPG alters the properties of the aerogels, such as density, shrinkage, porosity, and modulus
• Aerogels with more than 30% PPG are hydrophobic with contact angles 90-124o
• Aerogels shrink the most with 60% PPG-400, resulting in the highest density, lowest porosity, and lowest surface area
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Dan H.
Acknowledgement Aerogel team members Dr. Mary Ann B. Meador Dr. Baochau Nguyen Stephanie L. Vivod Dr. Jarrod C. Williams Rocco P. Viggiano Drying & characterization Daniel Haas Linda S. McCorkle Daniel A. Scheiman Nathan G. Wilmoth Summer Intern Brittany Wilkewitz Funding Fundamental Aeronautics Program Hypersonic Inflatable Aerodynamic Decelerator Program (HIAD)
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Mary Ann
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Jarrod
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